This invention relates to integrated circuitry and to methods of restricting diffusion from one material to another.
Diffusion barriers are commonly employed in semiconductor wafer fabrication to restrict diffusion between materials, such as preventing diffusion of dopant from one material to another. Diffusion barrier layer materials can be conductive or insulative. Titanium nitride and titanium are example diffusion barrier materials which are conductive. Such materials can be used, for example, at the base of a contact over or to a diffusion region in a semiconductive substrate, and be positioned intermediate the diffusion region and an overlying conductive layer.
Diffusion barriers can also be crystalline or amorphous. When comprised of a crystalline material, grain boundaries of the crystals which extend all through the layer adversely impact the material""s diffusion barrier properties. This is due to potential pathways for diffusion of material along the grain boundaries being created from one surface of the layer to another. It would be desirable to develop methods and constructions which produce better barrier layer materials or constructions which are less susceptible to material diffusion along grain boundaries.
The invention in one aspect includes methods of restricting diffusion between materials. In one implementation, a method includes providing first and second different materials which are separated by a barrier layer capable of restricting diffusion of material between the first and second materials. The barrier layer being formed by forming a first layer of a third material over the first material. A second layer of the third material is formed on the first layer. The second material is formed over the second layer of the third material.
In another aspect, the invention relates to diffusion barrier layers. In one implementation, such a layer comprises a composite of two immediately juxtaposed and contacting, yet discrete, layers of the same material.
In another aspect, the invention relates to integrated circuitry. In one implementation, a semiconductive substrate has a conductive diffusion region formed therein. An insulative dielectric layer is received over the substrate and has a conductive contact formed therein which is in electrical connection with the diffusion region. The conductive contact comprises a conductive barrier layer proximate the diffusion region. The conductive barrier layer comprises a composite of two immediately juxtaposed and contacting, yet discrete, layers of the same conductive material.